Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) has been an established method for forensic glass fragment analysis since the 1990s, as glass is a common piece of evidence encountered in vandalism, traffic accidents or burglaries.[1] The currently used quadrupole-based method requires 6 ablation spots with 80 µm diameter, resulting in required glass fragments that are bigger than 400x200x100 µm, whereas case samples are often smaller.[2] Especially the thickness of a case sample can be a limiting factor, making it difficult to obtain enough data points to quantify the elements in the sample.  

In this work, a single pulse quantification method for float glass fragments is introduced. A 193 nm ArF excimer laser (GeoLasC, Lambda Physik, Goettingen, Germany) was equipped with a low dispersion ablation cell to ensure fast aerosol wash out. This was coupled with an ICP-TOFMS (icpTOF, Tofwerk, Thun, Switzerland) to enable quasi-simultaneous detection of all elements from Na to U and allow for a representative measurement of the fast ion cloud.[3]  As a first proof of concept, this method was used to match and mismatch 10 fragments from 10 different case samples, with a sample volume requirement reduction to 100x100x33 µm, showing a reduction of sample material from approx. 20 µg to 0.8 µg, while maintaining similar success.  

The single pulse approach results in more data points and offers more spatial information, allowing for further statistical treatment that was not possible previously.

[1] R. J. Watling, B. F. Lynch and D. Herring, J. Anal. At. Spectrom., 1997, 12, 195–203.
[2] P. Weis, M. Dücking, P. Watzke, S. Menges and S. Becker, J. Anal. At. Spectrom., 2011, 26, 1273–1284.
[3] H. A. O. Wang, D. Grolimund, C. Giesen, C. N. Borca, J. R. H. Shaw-Stewart, B. Bodenmiller and D. Günther, Anal. Chem., 2013, 85, 10107–10116.